Signaling system



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SIGNALING SYSTEM Filed Jan. 10, 1939 12 Sheets -Sheet 1 ATTORNEYS April 1, 1941.

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ATTORNEYS April 1,' 1941. c. J. FITCH SIGNALING SYSTEM Filed Jan. 10, 1939 12 Sheets-Sheet 3 FIG.6C'

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C. J. FITCH SIGNALING SYSTEM Filed Jan. 10, 1939 12 Sheets-Sheet 4 INVENTOR iii/- ATTORNEYS April 1, 1941. Q F TH 2,237,140

SIGNALING SYSTEM Filed Jan. 10, 1939 lzsheets sheet 5 ATTORNEYS April 1, 1941. c. J. FlTCH SIGNALING SYSTEM Filed Jan. 10, 1939 12 Sheets-Sheet 6 INVENTOR V W A TToRNEYs April 1, 194-1. Q J rrc 2,237,140

smmuue SYSTEM Filed Jan. 10, 1959 12 Sheets-Sheet 7 FIG. 19.

INVENTOR ATTORNEYS April 1, 1941. c. J. FITCH SIGNALING SYSTEH Filed Jan. 10, 1939 12y Sheets-Sheet 8 |NVENT OR 4 2 C. J. FITCH SIGNALING S YSZ'EH Filed Jan. 10. 1939 April 1, 1941.

12 Shets-Sheet 9 NdE w n N 5 Q: fi in I x n M Q T 1.: n w r 1 m t r l MN FlhlL PIFIL TQJ HNJ N ATTORNEY April 1, 1941.

C. J. FITCH smmmue SYSTEM Filed Jan. 10. 1939 tmw //4-a lzshe is-sneet n PHASE 2 /msz 7 Ply/455a C. J. FITCH sI GNALmG'sYs'rEu Filed Jan. 10, 1939 April 1, 1941.

12 Sheets-Shea? 12 SEN k kg m ATTORNEY Patented Apr. 1, 1941 SIGN 1 SYSTEM Clyde 3. Fitch, Endicott, N. r assignor to mmi national Bus Machines Corporation, New York, N. Y a corporation of New York Application January 19, 1939, Serial No. 250,092

This invention relates to signaling systems and more particularly to a system adapted for two way communication.

The instant application constitutes an improvement over the signaling system described in the copending application, Serial No. 756,443, flied December 7, 1934, now Patent 2,153,178, issued April 4, 1939, wherein a plurality of normally nonconductive signaling channels are provided at a transmitting and receiving station; each channel including an electric discharge device, and wherein individual sources of fluctuating voltages are transformed into polyphase voltages which at each station are impressed upon the signaling channels for conditioning the channels periodically and cyclicalLv at mutually exclusive intervals for control purposes. Signal initiating and indicating means are described in detail hereinbelow and are shown to control selectively the signaling channels at the transmitting station to render them conductive upon operation of the signal initiating means for initiating code combinations of control signals which are efiective to. render the receiving signaling channels conductive in accordance with the receipt of the signals for controlling selectively the signal indicating means. It was mentioned that individual sources of voltages are provided for conditioning the signaling channels and assumed that the said remotely situated sources of voltages are obtained from synchronous distribution systems.

It is known that for certain applications that such synchronous sources of voltages are not available and that therefore, additional provisions must be made for controlling the synchronous conditioning of the said signaling channels. In the instant application, means will be disclosed whereby t'ze transmitting station controls the synchronous conditioning of the signaling channels at both stations.

For this purpose, certain of the available signaling channels are employed for synchronizing purposes, thus, at the transmitting station a predetermined number of the signaling channels are normally maintained non-conductive and disconnected from the transmission medium for signal control purposes as described in the said copending application, and that, for example, a single signaling channel is connected at all times to the transmission medium so that, upon the periodic and cyclic conditioning of the last mentioned channel, periodic synchronizing signals are impressed continuously upon the transmission medium. In this manner, the normally non-conlations of a predetermined frequency.

ductive channels are selectively rendered conduc-- tive in accordance with the operation of the signal initiating means for initiating a periodically timed control signals, and the selected channel for synchronizing control purposes is efi'ective continuously for initiating periodic synchronizing signals. At the receiving station, corresponding signaling channels are provided which normally are non-conductive, and which are conditioned periodically and cyclically in synchronism.with the conditioned signaling channels at the transmitting station. Upon receipt of the timed signals, initiated upon operation of the signal initiating means, such signals are-properly segregated and efiective to render the corresponding signaling channels conductive at the receiving station which, in turn, are effective to control the associated signal indicating means. A corresponding synchronizing signal channel is provided at the receiving station to be responsive to the periodic synchronizing impulses which upon receipt thereof are efi'ective for controlling the conditioning of the signaling channels at this-station.

At each of the stations an independent fluctuating supply source is provided in the form of an oscillation generator adapted to produce oscil- In the instant application the oscillation generators referred to are shown in the form of electronic oscillation generators; it is understood that other forms of generators of fluctuating power supplies may be employed if desired. Provision is made whereby the oscillation generators referred to are controlled and excited by the periodic synchronizing signals. Therefore, it will be seen that the synchronizing channel at the transmitting station is adapted to be conditioned by the electronic oscillation generator thereat so as to be conductive at periodic intervalsto initiate synchronizing signals at such intervals and that the synchronizing signals are efl'ective in turn to sustain further generation of the oscillations produced by the electronic oscillation generator thereat. Receipt of the periodic synchronizing signals at the receiving station is effective to excite the oscillation generator provided thereat which in turn is then eflective to generate oscillations of a frequency corresponding to that of the oscillations generated at the transmitting station which in turn are then impressed upon the individual signaling channels including the.

synchronizing channel tov condition these channels and control the conductivity thereof. Itwlll be seen that the synchronizing'channel is rendered conductive periodically to sustain further generation of the oscillations at the receiving station. In this manner, it is possible to provide a signaling system which is self-contained and which can be operated in synchronous relationship irrespective of the normal power sources, the features of which are claimed in copending application Serial No. 239,838, filed November 10, 1938.

It will be shown how to arrange the system Just described for two way transmission purposes. To this end, a control switching means is provided with a plurality of control circuits associated therewith for-selectively connecting the series of signaling channels for initiating or receiving control signals. Utilizing the common signaling channels for both initiating and receiving the signals, obviously simplifies the circuit arrangement and reduces duplication of the control devices to a minimum. For illustrative purposes. since the signaling system disclosed herein' -is particularly suited for printing telegraph systems, signal initiating and receiving means will be shown embodied in suitable tele-registering devices employing a plurality of permutation units which may be conditioned upon operation of the character keybars for controlling the signaling channels for initiating character code signals or may be controlled so that, upon receipt of the code signals, controlling the selection and Therefore, an object of the present invention resides in the provision of a signaling system comprising a series of normally non-conductive signaling channels which are conditioned periodically and cyclically for controlling the conductivity of the channels by utilizing a fluctuating power supply therefor, and associated control means whereby the signaling channels are conditioned for either signal transmission or reception purposes.

Another object of the present invention resides in the provision of a tele-registering device which may be conditioned for controlling the said signaling systems for initiating the character code signals or for being controlled by the signaling system in accordance with code signals received thereby.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by way of example, the principle of the invention and the best mode, which has been' contemplated, of applying that principle.

In the drawings:

Fig. 1 is a sectional view showing the standard mechanism of one preferred type of recording unit.

Fig. 2 is an exploded view showing the normal position of certain of the parts of the power opele ents are exa erated to show clearly the relative positions thereof.

Fig. 3 is a sectional view of one group of permutation bars cooperating with the power operated units.

Figs. 4 and 5 show the elements in Fig. 3 in operated positions.

7 Figs. 6 to 6-1! are detafl views of the transmitting permutation bars.

. Fig. 'l is a detail view showing the arrange ment of the contact controlling means.

Fig. 8 is a detail view of a selector member.

Fig. 9 is a detail of a selector finger.

Fig. 10 is a sectional view along the lines Iii-ll of Fig. 11.

Fig. 11 is a plan view of the transmitting unit.

Fig. 12 is a sectional view along the lines l2-l 2 of Fig. 19.

Fig. 13 is a sectional view showing the receiving permutation unit associated with the record- Fig. 14 is a detail view of the driving gears of the receiving unit.

Fig. 15 is a perspective view of the receiving permutation bar unit.

Figs. 16 to 18, inclusive, are detail views of the clutch mechanism shown in Fig. 15.

Fig. 19 is a plan view of the receiving permutation unit.

Fig. 20 is a partial sectional view of the transmitter receiver unit.

Fig. 21 is a circuit diagram showing diagrammatically the circuit arrangement of the signaling and synchronizing channels of the transmitting and receiving stations.

Fig. 22 shows diagrammatically one form of a phase-splitting device which may be employed at the transmitting and receiving stations.

Fig. 23 shows diagrammatically the individual control means for the signaling channels at the transmitting station.

Fig. 24 to Fig. 26, inclusive, show various forms of impulse generators which may be employed in the present signaling systems.

, Fig. 27 to' Fig. 33, inclusive, show the voltag wave shapes impressed on various sections of the control circuits.

Fig. 34 shows graphically the developed phase displaced impulses representing the differential times at which the electric discharge devices at both the transmitting and receiving stations are rendered conductive.

Fig. 35 shows one method of connecting the signaling circuits at each station for two way transmission purposes.

Signal initiating and indicating mechanism Before describing the signaling system circuit arrangement, the signal initiating means and indicating means will now be described.

For illustrative purposes, the invention is shown as embodying a well known type of recording unit, which may be similar in construction to the Electromatic typewriter, shown and described in detail in U. 8. Patent #1,'777,055, and hence requires only the following brief description.

Referring to the drawings and particularly to Fig. 1, well known means are provided for actuating the typebars l 8 comprising a constantly rotating roller ll, cooperating with a series of individual power units each comprising a cam II. the engagementof the canis with the roller being controlled selectively by the character keyerated units. Several structural features of the ars"- Any suitable means may be provided to rotate the power roller in the direction indicated by the arrow, which is adapted to cooperate with two rows of cam units arranged in the front and rear of the roller. The cam ll may be provided to be pivoted on one arm of a bell crank lever l2 which is pivoted in the frame of the recording unit, as indicated generally by reference character iii, the other arm of the said bell crank lever being operatively connected with an arm of hell crank lever H by means of link i5. Another arm of the said lever I4 is connected to the typebars I6 in'a well' known manner, so as i to effect operation of the typebars or any other suitable means connected to the bell crank levers upon selective operation of the controlling keybars II.

The pivoted bell crank lever i2 is operated by the associated cam Ii whenever the latter engages the driven roller; the engagement of the cam with the roller is controlled by means of the associated control keybar I! in a manner which will now be briefly described.

Referring now to Fig. 2, the cams occupy normally the positions shown in this figure, which represents one of the rear banks of the units. In this position the impeller-arm i8 is urged, by the associated coil spring l9, against one of the impeller-lugs 20, which at the time is in the lower position, and tends to turn the cam l I in a clockwise direction. This is prevented, however, by the engagement of one of the detents 2! on the cam, with the upper stop lug 22 on the stop lever 23. bar is operated, the bifurcated lower end (Fig. l) of extension arm 24 associated with one of the said keybars i1 engages an arm 25 at the upper end of the stop lever 23 which is provided with an offset projection at its end which extends laterally through an opening in the bell crank lever i2. The arm 25 of the stop lever 23 is then swung rearwardly or to the left as viewed in Fig. 1 about the pivot 26 and its lower end forwardly or to the right as viewed in this figure, thus releasing the cam which then turns under the influence of the spring urged impeller-arm i8. In doing so the upper serrated lobe of the cam is brought into engagement with the power roller, which turns in a counterclockwise direction and therefore causes a continued rolling movement of the cam until the high point has been reached and passed. This causes the whole cam unit to swing around the pivot i3 so as to pull down the corresponding link and actuate one of the typebars or any other mechanism with which the cam unit may be connected.

After the high point of the cam is passed, the cam loses contact with the roller, but the said impeller-arm l8 tends to continue the rotation thereof by engaging the second impeller-lug 29 of cam il until the second detent 21 engages one of the stop lugs. Since the half rotation of the cam consumes only a small fraction of a second, it is diflicult to release the keybar within this short interval, so that it is the lower lug 28 which is first engaged, but upon the release of the keybar and the return of the stop lever 23 to normal position, this lug 28 disengages the detent, whereupon the impeller-arm rotates the cam slightly, and the said detent then engages the upper stop ing 22.

It is obvious then that depression of a keybar releases the revolubly mounted cam to engage and be actuated by the power roller in turn operating the associated bell crank lever and its attached links to cause the associated mechanism such as the typebars and other operating mechanisms to be operated. It is tobe understood that an individual cam unit is provided for each typebar or other functional mechanism associated therewith.

The action of the cam mechanism has been described with respect to one of the rear bank of cam units; in the case of those ofthe forward bank the operation is analogous, but the directions of movement and the order of operation of the stop lugs is reversed. For example, if the bifurcated arm 24--a is positioned to engage the arm -11. at the upper end of stop lever 23-11 by virtue of operations of the associated keybar, the said arm is positioned rearwardly or to the left as viewed in Fig. 1, and the lower end of the stop lever 23a is moved forwardly, that is, to the right as viewed in the said figure. This said operation is effective to release the cam', by virtue of positioning the lower stop lug 28-0 out of the path of detent 2l--a, thus permitting the spring-urged impeller-arm 18-11. to rotate the cam slightly in a clockwise direction to effect If, however, the corresponding keyengagement of the lower lobe of cam ii and power roller. Upon completion of a half revolution of the cam II, the second detent 2|-a engages first the upper stop lug 22a while the stop lever 23--a is in an operated position, but upon release of the associated keybar and the return of the said stop lever to normal positions, this lug 22-41 disengages the said detent and the impeller-arm rotates the cam slightly so that the said detent then engages the lower stop lug 28a, as shown in the figure. In this manner the bell crank lever i2-a is rotated about the pivot i3--a to operate the associated typebar or any other mechanism associated therewith. For further structural details of the cam units, reference should be made to the above mentioned patent.

The description just set forth related to a standard typewriting unit and the mechanical connections between the controlling keybars and typebars. The permutation bar units condition the transmission medium in accordance with the selected characters and control the recording of the said characters at the transmitting station, and the permutation bar unit which is controlled by the conditioned medium to select the keybars in accordance with the conditioned medium and thereby record the characters accordingly will now be explained. It isto be noted that the described mechanical linkages between the keybars and typebars are not modified in any manner so that the unit can be conditioned for three different types of operations, namely, as a printing telegraph transmitting printer unit, as a printing telegraph receiving printer unit, and as a standard typewriting or recording unit.

Referring now to Figs. 3 to 11 and'20, the transmitting permutation unit associated with the Electromatic typewriter will now be described.

The bell crank levers i2 are provided with arms 30 depending therefrom and on which are rotatably mounted individual cam rollers 3| which are displaced whenever the associated bell crank levers i2 are actuated by the released cams ii. The cam rollers 3| are positioned so as to be adapted to position or displace control members 32 whenever the said rollers are displaced, for a purpose now to be set forth.

The permutation bar mechanism will now be described and by referring to Fig, 11 is shown to comprise generally a plurality of permutation bars or rods 33 provided with keys or fingers 34 and a plurality of selector members 32 (see Fit. 8) provided with tabs or studs 35. More specifically, a permutation rod comprises a shaft 36 flat on one side as shown by reference charact'er 31 co that the tapered keys or fingers 34 having correspondingly shaped openings at the untapered section (see Fig. 9) may be fitted on the said shaft, so that the keys are positioned or rotated in accordance with the shaft. Tubular spacings 38- are provided for accurately spacing' the various keys on the shaft 35. It is to be noted that the keys are selectively arranged on the shafts so that ,some of the tapered ends extend or protrude above the shaft and some extend below or depend from the shaft, the purpose of which will be understood as the description progresses (see Figs. 6 to 6E) Shafts 35, of which, in the present example, six are shown, are rotatably mounted in the end plates 39 which also support grooved rods 40. This unit just described and-generally designated 4| (Fig. 11) is pivotally mounted at'42 to the typewriter frame by members 43 and is adapted to be locked or fixed in an operating position by being secured to the typewriter frame by means of the bolts and nuts shown generally at 44.

It was mentioned that a plurality of selector members. 32 are provided and adapted to be engaged by the cam rollers 3| to be positioned thereby. The selectors 32 are shown slidably mounted on the grooved rods 40 and are all identical in structure. A detail of a selector 32 is shown in Fig. 8 and comprises a member provided with similar forked or bifurcated ends 45; at one end thereof extensions 46 are provided and as shown are adapted to be engaged by the cam rollers 3| to be positioned thereby. Each selector is provided with a rectangular opening 41 so as to be able to straddle the permutation bars 33; and also along one section of the selector member equally spaced tabs or studs 35 are fixed thereon, three studs on each side of the member and alternately positioned thereon.

The selectors 32 are slidably mounted on the grooved rods 40 and held in alignment or position by the grooves. Some of the selectors are arranged so that the studded sections of the selectors are above the bars 33 and others are arranged so that the studded sections thereof are below the bars 33; that is, the selectors are positioned so that the studs of somelie in the plane of the keys extending below the bars 33, and so that the studs of some lie in the plane of the keys extending above the bars.

The purpose of the described arrangement is to permit the studs 25 to engage certain of the keys 34 when the selectors 32 are displaced due to the typewriter cam operation to rotate the engaged keys and thereby rotate the shafts associated with the said keys. The particular keys and shafts rotated upon displacement of the selected selectors depends upon the permutation code selected. The reason for alternating the positions of the studs 35 will now be understood, namely, so that proper clearance is provided for the keys 34 attached to the permutation bars, when the keys are displaced through their angle of rotation, so that during said rotation studs on other selectors are not engaged by the associated keys fixed on the rotated shafts.

It is preferred when the selectors described are used in conjunction with the Electromatic typewriter that the studded sections are alternately arranged to be positioned above and below the permutation bars, respectively, due to the close spacing of the typewriter cam members; therefore, in accordance with this arrangement, it will be seen that the front typewriter 'cains displace selectors 32 which are arranged so that the studs thereof engage the keys extending below the bars 33 to rotate the said keys and associated shafts in a counterclockwise direction and that the rear typewriter cams displace the selectors 32 which are arranged so that the studs thereof engage the keys extending above the bars 33 to rotate the said keys and associated shafts in a coupterclockwise direction. Upon displacement of the associated shafts and selectors, provision is made to return them to the normal inoperative position by means of springs 43 attached to the bars 33 and posts 49 mounted on the end plates 33 and the springs 50 (Figs. 3 and 5) interconnecting the adjacent selectors 32.

Attached to each end plate 39 is a switch unit 5| comprising three individual switches which may be of the single pole, double throw type. The switch arms 52 are pivoted at 53 and are normally in position to engage contacts 54. The arms 52 are provided with insulating heads and are engaged by keys 56 Fig. 10 (similar to keys 34) depending from the shafts 36 so that normally the switch arms are positioned against the tension of springs 51 which are attached to the switch arms and the housing of the switch unit 5| to engage the contacts 54; however, upon rotation of the bars 33 in a counterclockwise direction the keys 55 also are rotated in a similar direction, thereby permitting the springs 51 to rotate the switch arms 52 in a clockwise direction so that contacts 58 are engaged by said arms. The tensions of springs 48 are greater than the tensions of springs 51, therefore, when the bars 33 are returned to normal position by the associated springs, the keys 56 return the switch arms 52 to the normal position describe to engage contacts 54.

Referring now to Fig. 4, one of the front cams II is shown in an operated position and let it be assumed due to the depression of a certain keybar. The displacement of the bell crank lever |2a causes the cam roller 3| on extension arms 30 to displace a selector 32 to the right and thereby engaging and displacing the keys 34 attached to permutation bars 33 Nos. 2, 3, 4 and 5, causing the shafts to be rotated in a counterclockwise direction and releasing the corresponding switch arms 52 to engage the associated contacts 58.

In Fig. 5, one of the rear cams is shown in an operated p sition due to depression of the keybar corresponding to a different character, to displace a selector 32 to the left engaging and rotating in a counterclockwise direction the keys 4 fixed to the permutation bars 33 Nos. 2, 3, and 4, to release the associated switch arms 52 to engage the contacts 58.

In this manner, combinations of signal conditions may be initiated in accordance with the chosen permutation code and due to the operation of the associated keybars not only are the associated permutation bars displaced by the power operated units but the latter are also effective to operate the corresponding typebars to effect recording of the characters corresponding to the character signal conditions represented by the operated permutation bars. The linkages operating the typebars have not been altered, so that when the machineis not conditioned for transmitting purposes the operation of the keys causes the typebars to be operated in a normal manner. The means for conditioning the machine will be described hereinafter; however, it is noted that the signal conditioning means or the contacts operated by the permutation bars must be disconnected from the transmission medium oecause, upon any operation of the typebars and the power operated units the selectors and described permutation bars are always operated,

that is, upon operating the machine as a standard typewriter or as a receiver unit the said described unit is operated.

The permutation unit adapted to be controlled by the conditioned transmission medium will now be explained. This said unit is associated with the operable keybars of the machine and is adapted to select and operate the keybars to operate the common power operated units and typebars which are operated when the machine is conditioned for signal transmitting purposes or for standard typewriting purposes.

Referring now to Figs. 12 to 20, the said unit is shown to comprise generally a. plurality of round slotted shafts or bars 66, the slots 6| of which are arranged diametrically opposite one another. The said bars are normally maintained inoperative so that the control levers 62, one for each keybar and attached thereto by link 63, are locked in an inoperative position. Gear units v64 (Fig. 14) are provided at each end of the permutation bar device, comprising three sets of gears, one for each shaft or bar 68. The gears 65, 66 and 61 are rotated continuously by drive ears 68 and are connected to the associated bars 66 by individual clutches 69 (Fig. 15) to drive said bars one revolution. The clutches 69 are controlled by magnets 10 which are energized by control signals and in combinations in accordance with the preferred permutation code. During the rotation of the selected bars 66, certain slots 6| disposed thereon are presented under the control levers 62 so that one control lever is selected and permitted to drop in the channel provided by the slots which are in alignment, operating the control lever and its attached keybar lever, thus causing the character to be recorded.

The permutation bars 66, of which six are shown, are supported in-the end plates 1| (see Fig. 12) attached to the gear units 64 which are secured to the supporting castingindicated generally at 12. To prevent sagging of the bars, central supporting posts 13 are provided. The con trol levers 62 are positioned over the permutation bars 69 (Fig. 13), and are pivotally supported at the ends thereof by rod 14 suitably supported by members 15 attached to the supporting casting Individual springs 16 are attached to the levers 62 to urge the levers against the permutation bars 60. The levers 62 at the other ends thereof are linked to the keybar by connecting links 63, and therefore it will be seen that upon depression of a control lever 62 by spring 16 the link 63 will be moved downwardly to lower the attached keybar and causing the associated power operated unit and typebar to be operated. The levers 62 are kept in correct alignment by means of the comb member 11 attached to the said supporting casting.

The entire supporting casting 12 is pivotally secured to members 16 so that the entire permutation bar unit may be rotated about the pivots 19 (Fig. 20) by removing nuts 19a. The pivot line through the pivots 19 is in line with the center of attachment of links 63 and levers 62 so that the said unit may be hinged downwardly without disturbing the link connections to the keybars.

The permutation bars are slotted in accordance with any desired permutation code and are arranged so that upon rotation of certain of the bars, one control lever 62 is selected and permitted momentarily to be depressed into the slots by spring 16 thereby depressing the attached link 66 and keybar 11. Referring to Fig. 15, the rotation of bars 66 Nos. 2, 4 and 6, will cause the slots of all the bars to be aligned under the particular control lever 62 shown, thereby permitting said lever to be lowered into the slots momentarily to depress the associated link and keybar, causing the corresponding typebar to be operated.

The bars-are rotated as follows: The power driven roller I6 of the typewriter is adapted to rotate the shaft by means of the connecting belt 6 I Attached to said shaft is a pair of driving gears 66, the gears positioned so as to engage the gears 66 (Fig. 14) in each gear unit 64. The gears 66 are adapted to rotate the gears 65 and 61. Each of the gears 65, 66 and 61 is attached to individual stud shafts 82 (Fig. 15) upon which are mounted ratchet gears 63. Associated with each ratchetgear 83 is a clutch unit 69 which is secured to the permutation bar 68. A clutch unit is provided for each bar. The principle of operation of the sets of clutch units and gear units are identical and consequently only one set need be explained. It will be seen from Fig. 14 that the directions of motions of the clutch gears 65, 66 and 61 are different, and because of this fact the clutches 69 are made right-hand and left-hand to correspond thereto.

A controlling magnet 10 is provided for each clutch 69. Referring to Figs. 12 and 15, the magnet 18 is provided with an armature 84 secured to a clutch stop arm 65. The said arm, while'the magnet 10 is deenergized, is adapted to engage the doglift lever 66 which maintains the dog 81 in the position shown in the figure to prevent engagement of the tooth 66 on the dog and the ratchet gear 63.

The clutch is shown to comprise (see Figs. 16

tends to urge or maintain the dog 81 to the right as viewed in Fig. 17. The dog 61 and housing member 69 are recessed so as to receive the dog lift lever 66 which, when inserted in the housing member, is adapted to be rotated slightly or pivoted about one end thereof. The other end of the dog lift lever extends beyond the housing member and is arranged to engage the stop arm 65 whenever magnet 18 is deenergized. Movement of the dog lift lever 86 moves the recessed dog 61 and when blocked by the stop arm 65 as shown in Fig. 15 positions the dog 61 to the extreme left-hand position against the action of spring 9|. A spring-pressed stop 92 engages a notch 93 provided in the housing member 89, preventing the bar 66 to be rotated in a clockwise direction as viewed in the figure, thereby locking the clutch unit so long as the magnet tions in time of arrival of the signals.

84 is attracted and positions the stop arm 85 downwardly about the pivot 84 out of engagement with and out of the path of dog lift lever 88. The spring 9| then forces the dog 81 to the right as viewed in Fig. 15 whereby tooth 88 moves into engagement with the constantly rotating ratchet gear 83.

The signal condition impressed upon the mag net 10 lasts momentarily, so that the stop 85 is positioned in the path of the dog lift lever 88 before one revolution of the clutch has been completed. As the clutch is rotated by the gear 88 and completes its revolution, the dog lift lever engages the stop 85, and as the clutch continues its rotation with the lift lever 88 held stationary by the stop 85, the said lift lever is rotated about its end positioned in the housing member 89 to slide the tooth 88 of dog 81 out of engagement with the ratchet gear 83. When the tooth 88 is brought out of engagement with the said ratchet, driving power is removed from the clutch and permutation bar. The spring 8| within the dog 81 normally would have a tendency to rotate the permutation bar in a reverse direction and permit the tooth 84 to again engage the ratchet gear; however, as previously explained the clutch and bar 80 are locked in the inoperative position by means of the stop 92. Due to the relative high speed of operation, when the toothed dog is forced out of engagement with the ratchet by means of the stop 85, the momentum of the rotating permutation bar and clutch is suillcient to rotate the bar and clutch slightly beyond the position where the tooth 88 Just becomes disengaged from the ratchet gear: this carry-over is sufficient to permit the spring pressed stop 92 to engage the notch 93 locking the clutch and bar against reversed rotation and insuring sufflcient clearance between the dog tooth and the ratchet so as to prevent chattering.

The remaining permutation bars are rotated in a like manner upon energization of the associated clutch magnets 10. The magnets are energized practically simultaneously so that when a particular combination of signals'causes certain of the magnets to be energized, the corresponding permutation bars are permitted to'be rotated one revolution, permitting one control lever 62 to drop in the aligned slots on the permutation bars, thereby recording a character on the power operated typewriter accordingly.

The design of the permutation bar unit should be such that the stroke of the lever 82 is about twice as great as necessary to operate the typewriter keybar. In this manner the clutches are permitted a wide margin of operation and provides suflicient tolerance to allow for variations in timing of the different magnets due to variawith reference to Fig. 13, it is seen that when the permutation bars 2, 4 and 8 rotate one revolution, the first 90 thereof, the levers B2 are all maintained in a locked position, the next 90 permits the selected lever to be pulled downwardly by spring IS, the next 90 locks up all the levers again and during the last 90 the bars are positioned as shown in the normal position. It is seen, therefore, that upon reception of a signal the bars are rotated, but even in this event all the control levers are maintained in a locked position except the selected one, in this manner making it impossible to depress more than one control lever and its associated keybar at a time.

It should be mentioned that the keybars I1 are each provided with an elongated slot so positioned that the connecting pin 88 secured to link 88 is eifective to cause depression of the keybar when the control lever 82 is lowered into the aligned slots in the permutation bars. This said slot also permits the keybars II to be depressed manualiy without disturbing the link 83 and lever 82, to eflect operation of the power operated units and corresponding typebars. In the described manner the machine can be conditioned not to be operated by the conditioned transmission medium yet be operated manually as a standard typing unit. The description thus far dealt with the mechanical elements of the machine and their arrangement so that the machine can be operated as a transmitting unit, a receiving unit, and a standard typing unit, the features of which are claimed in copending application Serial No. 175,370, dated November 19, 1937 now Patent 2,181,940 issued Dec. 5, 1939. The signaling system will now be described.

General description of signaling system Referring now to Fig. 21, the signaling system shows and comprises a plurality of signaling channels including electric discharge devices T-l to T-8 and R-l to 'R-8 at the transmitting and receiving stations designated A and B, respectively. The series of electric discharge devices are shown associated with the phase-splitting transforming means generally indicated by the reference characters 8 and llll-a which, for the instant application, are similar in design and shown in detail in Fig. 22. Individual sources of fluctuating power are impressed upon the phase-splitting transforming means which are effective to generate phase displaced voltages which, in turn, are impressed upon the associated electric discharge devices. The said discharge devices at both the transmitting and receiving stations are conditioned for controlling purposes by the fluctuating power supply periodically and cyclically at mutually exclusive intervals. The power supplies referred to are generated by the electronic oscillation generator systems which are indicated generally in the figure by the reference characters I and Ill-a, designating the electric discharge devices and the associated circuits which are adapted to generate oscillations of a predetermined frequency. The oscillation generator systems at both the transmitting and receiving stations are similar in design; therefore, hereinafter it will be suillcient to explain in detail the circuit arrangement and operation of only one of these systems. The electric discharge devices at the transmitting station are rendered conductive selectively upon operation of the signal initiating means described hereinabove and generally indicated by the reference character 54.

It is to be noted that normally the signal. initiating means 54 maintain the electric discharge devices TI to T8 disconnected from the transmitting circuit arrangement whereas the synchronizing channel including the electric discharge device T8 is at all times connected thereto for impressing continuously thereon the periodic synchronizing impulses. It is also to be noted that the synchronizing channel is effective at all times to impress the initiated periodic synchronizing signals upon the associated oscillation generator generally designated by the reference character ill, in this manner sustaining further generation of the oscillations which in turn are effective for controlling the conditioning of the signaling channels.

At the receiving station the devices R-I to RF-G are rendered conductive in accordance with the control signals received for controlling the energization of the signal indicating control means described hereinbefore and indicated generally by the reference character 10. The synchronizing channel at the receiving station including the electric discharge device 13-8 is controlled continuously at periodic intervals by the received synchronizing signals for controlling the energization or excitation of the associated oscillation generator generally indicated by the reference character III-a. The oscillations generated thereby are of the same frequency as the generated oscillations at the transmitting station, and are in synchronism there with so that, when the said oscillations are impressed upon the signaling channels at the receiving station, these channels are conditioned periodically and cyclically at the same intervals that the corresponding channels of the transmitting station are conditioned. Thus, it will be seen that the initiated periodic synchronizing signals are effective tocontrol the excitation of the oscillation generators at both stations, in this manner maintaining synchronous operation of the oscillation generators and, of. course, in turn maintaining synchronous conditioning and operation of the associated signaling channels of the transmitting and receiving stations.

Phase transforming means Referring now to Fig. 22, the phase transforming means associated with the signaling channels which may be employed at both the trans- 1 mitting and receiving stations will now be described.

The phase transforming means is shown to comprise two primary windings H4 and II! and the associated, secondary windings Ill-a to Ill-j and I I5--a to II5-f, respectively. In the circuit including the primary winding I I4, a condenser I I6 is included, and in the circuit including windings II|--b, Ill-c, III-e, IIlj of voltages equal to The secondary windings I Iii-a to I I5---! associated with the primar windings H5 are similarly rated and therefore, when connected as shown in the figure, the output voltages of the connected secondary windings are all of equal values. It is evident from the description thus far, and from the circuit arrangement shown in the figure, that four different phases, equally spaced electrically, namely, forty-five degrees apart, are developed. The phase directions vectorially are shown by the arrows for each of the phases in the said figure. It is to be noted that eight secondary outputs are provided and for this reason the output circuits of the secondary winding supply source.

ings are arranged in pairs. Thus, two circuits each are provided upon which the same phases are impressed. such as the circuits indicated by the designations, phase 1 and phase 5, or those designated phase 3 and phase 7. The purpose of this arrangement will be understood as the description progresses.

Channel conductivity controlling means Referring now to Figs. 24, 25 and 26, the operation of an individual electric discharge device and the associated circuits which may be connected to any one of the secondary output circuits of the said phase transforming means will now be described, and is shown to comprise an electric discharge device T equivalent to a full wave rectifier and triode in one envelope and which is well known in the art, commonly referred to as a duplex diode triode type." The diode plates I20 are joined to the terminals of any one of the said secondary windings of the phase transforming means, in the example chosen, indicated at III-a, the center tap of which is connected to the grid control element I22 of the device T, and by means of the resistor I23 is also joined to the cathode element I24a thereof. It is evident from this description that normally the grid element of the device is at zero bias, since no current is impressed upon resistor I23; therefore, upon closure of the signal initiating means shown as the contacts II2, a momentary current flow is established in the triode plate circuit as follows: from the positive terminal of the battery a to the resistor b, anode and cathode elements of the device T, to the negative terminal of the said battery. This described condition exists in the circuit for only a comparatively short time because the bias of grid I22 remains no longer at zero value, and is not a constant factor but varies in a timed relationship with thefrequency of the fluctuat- The said supply source by means of the winding II4--a is impressed upon the full wave rectifier section of the device and the rectified voltage impressed upon resistor I23 immediately drives the grid bias negative with respect to the cathode. The value of the resistor I23 is adjusted so that before the grid bias becomes efiective to reduce the plate current to substantially zero value, a pulse is impressed upon the output circuit just traced so that a short signal impulse is impressed upon the output circuit associated with the resistor b. It is understood now that as the signal initiating means H2 is maintained in an operative position, the device T is rendered conductive periodically so that a series of short equally spaced impulses will be continuously impressed upon the said output circuit and that the frequency of the initiating signals is twice the frequency of the fiuctuating supply source. Referring to Figs. 27 to 29, the voltage wave forms impressed upon different, sections of the. circuit are shown; Fig. 27 represents the sinusoidal wave shape of the voltage impulses impressed upon the diode plates I20 of the device; Fig. 28 represents the rectified wave forms impressed on the resistor I23, and the wave form shown in Fig. 29 represents the impulses generated and impressed upon the output circuit of the devices each time the said device is rendered conductive which as described is at thbse times that the said voltage supply passes through zero value.

Referring now to Fig. 25, the electric discharge device T and the associated circuits are shown through the resistor I23.

similarly arranged as shown and described in connection with Fig. 24 with the exception of the additional provision of the condenser I24 connected between one of the diode plates I20 of the device and the associated cathode. It is evident now from the description just set forth that the grid element I22 of the device is at zero bias when the fluctuating supply impressed in the secondary winding II4a passes through zero, due to the fact that no current is passing It is at such periods that the device is conditioned to be conductive thereby permitting current to flow in the associated output circuit. The effect of the condenser I24 as shown in Fig. 23 will now be described.

When the polarity is such that current passes from the diode plate I20 connected to the condenser I24 to cathode, this current passes through the resistor I23 and also charges the condenser I 24 to the polarity as shown. At the end of this particular half cycle as the current passes through zero, the charge in the condenser maintains the grid of the device negative with respect to the cathode and is of such value as to be suflicient to permit no plate current to flow. The charge in the condenser leaks oil through the resistor I23, the value of the capacitor and resistor being such that the time constant of the circuit is adjusted so as to maintain the device non-conductive during the timed interval that the said half cycle of the power supply passes through zero, and during part of the following half cycle until the current passing from the other diode plate I20 to the capacitor and through resistor I23 has reached suflicient amplitude to maintain the device biased so as to be maintained non-conductive. At the end of the second half cycle the charge incondenser I24 has completely leaked off, and as the said half cycle passes through zero the grid bias is zero, thereby permitting the device to be rendered conductive momentarily. Thus, it is seen that during the transition period during the first and second half cycle, the device is continuously rendered non-conductive, and during the transition period between the second and third half cycles, the condenser having received no charge during the, second half cycle, or if any charge,

is in the opposite phase thereby having no effect upon the bias and 'thus permitting the device to be conductive as the fluctuating supply voltage passes through zero. The curve shown in Fig. 31 shows the wave shapes of the rectifled voltage across the resistor I23 in the circuit arrangement shown in Fig. 25. The effect of the condenser I24 is evident, namely, suppressing the alternate peaks of the rectified waves as shown, and as just explained, the suppressed waves are effective to maintain the bias of the device such as to render the device non-conductive, whereas the unsuppressed waves are effective to render the device conductive. Thus, it is seen that the device is rendered conductive one time for each complete cycle of the fluctuating power supply impressed thereupon, whereas without the condenser the said device would be rendered conductive two times during a complete cycle of a fluctuating power supply.

In Fig. 31, the impulses indicated therein are representative of the periods at which the device shown in Fig. 25 is rendered conductive and the short current impulses flowing in the output circuit of the device at such times, which is seen from the figure occurs at equally spaced timed intervals. Now assume that the condenser I24 is connected in the diode plate cireuit opposite to that hown in Fig. 25, for example, as shown in Fig. 26, between the cathode and the other diode plate I 20. With the condenser inserted in the circuit as shown in Fig. 26, it is obvious that the opposite peaks of the rectified wave forms will be suppressed and render the tube non-conductive. In Figs. 32 and 33, the wave forms are shown when the condenser I24 i included in the circuit as it is shown in Fig. 26. It is seen that the opposite peaks of the rectified waves are suppressed to render the device non-conductive at those particular intervals. The impulses represented in Figs. 31 and 33 indicate comparatively the timed intervals during which the device T is rendered conductive depending upon which diode plate circuit has the condenser I24 .inserted therein.

It is now understood that by inserting the condensers in the opposite legs of the diode plate circuits and impressing fluctuating supply sources which are in phase, or of the same phase, upon the discharge devices that two different and separate signal generating circuits are obtained for initiating two series of equally spaced impulses, said series of impulses being separate electrically.

Referring now to Fig. 23, the individual electric discharge devices TI to T8 are shown connected to the individual output circuits of the phase transforming means IIO designated phase 1 to phase 8. It is noted that the condensers I24 associated with the devices TI to T4 are connected in one leg of the individual diode plate circuits thereof and for the devices T5 to T8 are connected in the opposite legs of the diode plate circuits. It was mentioned that pairs of similar or like phases of the voltage sources are developed, for example, phases 1 and 5 are shown vectorially to be in the same direction. Therefore, by connecting the individual electric discharge devices and the associated circuits, as described, to the individual secondary output circuit of the phase transforming means, for example, to phases 1 and 5 and having the condensers I24 connected in the opposite legs of the. diode circuits as shown, it is understood that the devices TI and T5 are rendered conductive at such intervals to initiate series of control'impulses diametrically opposite in phase, that is, 180 electrical degrees apart, as shown in Fig. 34.

Thus, it will be understood without further detailed description that with the four difler-- ent phases developed by the phase transforming means and a twin or double set of secondary circuits, and by connecting the electric discharge devices and the associated circuits thereto, and connecting the condensers I24 inversely in the twin secondary circuits-that eight separate signal generating circuits are obtained to generate eight differently timed signal pulses for control purposes, said pulses being spaced or separated 45 electrically.

The signal initiating means 54 are shown connected to the anodes of the devices TI to TI and the common conductor I25, so that upon operation thereof the associated devices are rendered conductive to initiate the timed signal impulses and effect energization of the following circuit at the various timed intervals: from the positive terminal of the power supply designated C. to the conductor I25, anodes and cath- 

